In general terms, the present invention is a wheel-and-tire apparatus including a pneumatic tire mounted on a wheel rim, for mounting on a motor vehicle in place of a conventional single-tire or dual-tire assembly. The pneumatic tire of the invention has two or more circumferential tread sections which may have different tread patterns if desired, or may incorporate different materials having different physical properties. The invention also includes means for selectively varying the diameter of the tread sections such that the number of tread sections in contact with the road surface varies as well. The invention thus facilitates the selective use of tire tread designs and material compositions having different performance characteristics, as may be desired or preferred to suit particular road conditions or vehicle operating conditions.
Although the tread section diameter adjustment may be controlled manually, the present invention also provides for automatic tread diameter adjustment through use of sensors which are mounted in the vehicle and which sense one or more selected operational parameters (e.g., speed, acceleration, steering input, braking input, or other parameters capable of being monitored by sensors known in the art). The sensors transmit corresponding signals to a computer which, using a program stored in a memory in the computer, selects an optimal configuration of tread section diameters to suit the particular combination of operational parameters received from the sensors. The computer then transmits a corresponding signal instructing the tread diameter adjustment means to adjust the diameter of one or more tread sections in the assembly as required to achieve the selected configuration of tread section diameters.
Accordingly, in one aspect the invention is a computer-controlled variable-diameter the apparatus for use in association with a motor vehicle. In the preferred embodiment, the apparatus includes a pneumatic tire having an inboard sidewall and an outboard sidewall, plus two internal walls dividing the interior of the tire into an inboard air chamber, an outboard air chamber, and a central air chamber. The tire is mounted on a wheel rim that may be mounted on the wheel hub of the vehicle. The tire has a circumferential tread band extending between the sidewalls, and the tread band has two circumferential tread channels dividing the tread band into an inboard tread section, an outboard tread section, and a central tread section. Each internal wall is generally aligned with one of the tread channels.
The invention also features tread diameter adjustment means, for inflating or deflating a designated one of the air chambers while the tire is at rest or when it is rotating. The tread diameter adjustment means includes an actuator, a computer with a memory, and one or more sensors adapted to measure one or more selected vehicle operational parameters, such as vehicle speed, acceleration, engine speed, braking load, steering input, steering load, engaged transmission gear, tire pressure, tire temperature, and shock absorber load. Each sensor has a sensor communication link for conveying sensor signals to the computer, corresponding to measurements made by the sensor. Also provided is an actuator communication link, for conveying actuation signals from the computer to the actuator.
In accordance with the invention, the computer memory is programmed to store a tread configuration protocol comprising selected tread configurations corresponding to selected sensor signals or combinations of sensor signals. The computer is adapted and programmed to receive a sensor signal or signals via the sensor communication link or links, to select from the tread configuration protocol a tread configuration corresponding to the received sensor signal or combination of sensor signals, and to transmit a corresponding actuation signal to the actuator, via the actuator communication link. The actuator is adapted to actuate the tread diameter adjustment means, in response to and in accordance with an actuation signal from the computer, so as to inflate or deflate the designated air chamber as necessary to render the diameter of a selected tread section or plurality of tread sections larger than the diameter of the non-selected tread section or sections, so as to deploy the selected tread section or sections in operatively-effective contact with the road surface, in accordance with the selected tread configuration.
The tread configurations contained in the tread configuration protocol may include configurations wherein only the central tread section is in operatively-effective contact with the road surface, only the inboard tread section and the outboard tread section are in operatively-effective contact with the road surface, and all three tread sections are in operatively-effective contact with the road surface. In these embodiments, the designated air chamber may be the central air chamber. Alternatively, the designated air chamber could be the inboard air chamber, with the tread diameter adjustment means being further adapted to selectively inflate or deflate both the inboard air chamber and the outboard air chamber, so as to selectively inflate or deflate both the inboard and outboard air chambers as necessary to selectively deploy all three tread sections, only the inboard and outboard tread sections, or only the central tread section, in operatively-effective contact with the road surface, in accordance with the selected tread configuration.
In a further alternative embodiment, the tread diameter adjustment means may be adapted to selectively inflate or deflate any one or more of the air chambers, so as to selectively inflate or deflate the central air chamber and/or both the inboard and outboard air chambers as necessary to selectively deploy all three tread sections, only the inboard and outboard tread sections, or only the central tread section, in operatively-effective contact with the road surface, in accordance with the selected tread configuration.